An illustration of the BX-1 microsat attched to the Shenzhou 7 orbital module. (credit: CCTV)

China’s BX-1 microsatellite: a litmus test for space weaponization

by Brian WeedenMonday, October 20, 2008

In the wake of China’s recent successful spacewalk and safe return of their three taikonauts, there have been concerns floating around the Internet over the microsatellite that was released at the end of this mission. Called the BX-1 in the official satellite catalog, and also referred to as CompanionSat, it was a very small cube approximately 40 centimeters on a side (16 inches) and weighing around 40 kilograms (90 pounds).

Some observers have concluded that the BX-1 was actually a test of some of the capabilities required for a co-orbital anti-satellite (ASAT) attack.

The direct ascent ASATs which were used to destroy the Fengyun 1C weather satellite in January 2007 and the USA 193 spy satellite in February 2008 were fired from the surface of the Earth, travelled on a ballistic arc toward their target, and intercepted it at high speed. Total flight time from launch to impact for these types of weapons is usually less than 15 minutes when attacking low orbits. By contrast a co-orbital ASAT is actually put into orbit like any other satellite. After a certain period of time, the ASAT conducts a series of maneuvers to put it on a collision course with its target. A version of this developed and tested by the Soviet Union fired a cloud of small pellets at its target like a shotgun blast.

The facts behind the BX-1 mission are still coming to light, but here is a summary of what is known at this point. About two and half hours after the spacewalk, the BX-1 microsatellite was released from it resting position on top of the Shenzhou 7 module. This release was done via a spring, which is a very common method of deploying microsatellites due to its reliability and simplicity. At this point the BX-1 was not under active control and drifted away from the SH-7 to a maximum distance of around 100 to 200 kilometers after a few days.

Approximately four hours after its release, the BX-1 made its closest approach to the International Space Station (ISS) of around 25 kilometers. The SH-7 itself made its own close approach shortly thereafter coming within 36 kilometers of the ISS. In both of these cases, it is important to understand the difference in orbits between the vehicles. The lowest point (perigee) of the ISS was 347 kilometers and the highest point (apogee) of the SH-7 orbit was 336 kilometers. The SH-7/BX-1 and ISS were also in different inclinations: 42.4 degrees and 51.6 degrees, respectively. This means that not only were they at different altitudes but also their orbits intersected at about a 10-degree angle. There was no danger of collision.

The BX-1 was released a few minutes after the ISS passed in front of the SH-7. Two and a half orbits later, when the BX-1 was at its closest point to the ISS, it was still fairly close to the SH-7 and within view of China’s limited space surveillance network. It makes sense that the Chinese, just like NASA and the Russians, plan important events to occur over tracking stations. But some analysts have observed that if it was indeed a simulated co-orbital ASAT test, having the target in observation by the mother ship before launch is beneficial for last-minute targeting. It will be almost impossible to determine whether or not the positioning of the SH-7 and ISS at the launch of the BX-1 and close approach were coincidence or pre-planned, but there may be other explanations. Chinese TV indicated that it was timed to obtain the best lighting conditions for the optical camera on the BX-1 to be able to observe the SH-7 as it drifted away.

The similar altitudes of both the ISS and SH-7 arise from some of the peculiars of orbital missions.

Following a series of maneuvers, the BX-1 was in an orbit where it could observe the SH-7 orbital module and take images from a fairly short distance. Some reports have indicated that it was in a 4 kilometer by 8 kilometer “orbit” around the module. This is simply not possible within the laws of physics. In reality, both the BX-1 and SH-7 module were in almost exactly the same orbit around the Earth, with a slight difference in eccentricity. From the point of view of the SH-7 module, this resulted in the BX-1 appearing to orbit around the module with between four and eight kilometers of separation.

The similar altitudes of both the ISS and SH-7 arise from some of the peculiars of orbital missions. As you go higher in orbital altitude, the atmosphere exerts less drag on your spacecraft. This means you need to do fewer fuel-expensive maneuvers to re-boost. At 400 kilometers, orbital lifetimes are usually measured in a few months without re-boost. At 200 kilometers this drops to a few weeks. But while higher is better from a fuel conservation perspective, there is an upper limit on how high it is safe to orbit humans for long periods. No manned missions are designed to orbit above 400 to 500 kilometers for long periods of time due to the health risk posed by the Van Allen radiation belts, and in particular the South Atlantic Anomaly.

The inclinations of the two objects have similar constraints. The latitude of the launch site plays the biggest factor in determining this. The most efficient launch trajectory is due east from a launch site, which places the satellite into an orbital inclination equal to the latitude of the launch site. It is fairly easy to launch objects into inclinations higher than the launch site latitude, but it is very difficult to launch directly into lower inclinations.

The 51.6-degree inclination of the ISS was determined by the latitude of Baikonur Cosmodrome (also called Tyuratam), of 46 degrees. This is where the first module, Zarya, was launched from in 1998. Because Cape Canaveral is at a lower latitude than Baikonur at 28.8 degrees, it is possible for both the Americans and Russians to easily reach the ISS. Similarly, the 42.4 degree inclination of the Shenzhou-7 was largely determined by its launch site, Jiuquan Space Launch Center, at 40.6 degrees latitude in northern China. And yes, if necessary, the Chinese could easily launch into the same inclination as the ISS.

There are a few elements of the BX-1 launch and operations that do not correlate to what would be expected from a co-orbital ASAT test. As seen from the live footage and photographs, the cameras on board the BX-1 were focused on the SH-7 for much of its separation time. If it was indeed supposedly tracking the ISS for a simulated attack run, why were they not pointed at the ISS? Also, it is unclear what sort of data links were between the BX-1 and SH-7. The BX-1 was sending its imagery and communicating with the Shanghai Microsat Center, a different ground station than what the SH-7 was communicating with.

In addition to concerns over being a possible co-orbital ASAT, other observers noted that the BX-1 was a precursor to a satellite inspection craft. The best example of this type of satellite is the XSS-11, a small satellite the size of a dishwasher developed by the US Air Force Research Laboratory and launched in 2005. The XSS-11 was designed to be able to autonomously rendezvous with another satellite and observe it at close range with a variety of sensors, including high resolution LIDAR mapping.

The Air Force insisted the mission was a “technology demonstration” and noted that it had applications for determining satellite malfunctions and performing on-orbit servicing. But the similarities between XSS-11 and Project SAINT are palpable. SAINT (short for SAtellite INTerceptor) was a highly classified program in the 1950’s designed to rendezvous with enemy satellites, inspect them with video cameras, and possibly disable or destroy them.

This gets to the heart of the matter for space weapons: the basic technologies that can be used for peaceful and beneficial purposes can also be used for harm.

Another US satellite that was designed to perform autonomous rendezvous was the Demonstration for Autonomous Rendezvous Technology (DART). DART was also launched in 2005 and was intended to maneuver close to and conduct proximity operations around the defunct US Navy MUBLCOM satellite. A navigation error when DART and MUBLCOM were about 200 meters apart resulted in the two objects bumping into each other at a speed of around 1.5 meters per second, slow enough that neither object generated debris nor was destroyed, but fast enough to change the orbit of MUBLCOM significantly.

Was the BX-1 a technology demonstrator for satellite inspection? Was it a test run for a future Chinese rendezvous and docking mission with the ISS? Was it a test run of a co-orbital ASAT? Is XSS-11 the reincarnation of a Cold War-era ASAT program? Was DART a failed proximity operations mission or a successful co-orbital intercept?

All of these questions ultimately are both true and false, depending on the respondent’s point of view. And this gets to the heart of the matter for space weapons: the basic technologies that can be used for peaceful and beneficial purposes can also be used for harm. The same technology that allows the Russian Progress or European ATV to automatically rendezvous and dock with the ISS could also be used in a co-orbital ASAT. The same technology that is used for ground or sea-based ballistic missile defense can also be used as a direct ascent ASAT. These events are a litmus test that reveals what the observer wants to see.

This is the argument that many make against the feasibility of space arms control: because of the dual-use nature of so many space technologies, any arms control regime or space weapons ban is inherently unverifiable. But the flip side of that assertion is that any advanced space technology development is also a potential weapons program. And that has potential to lead to a space arms race as each state attempts to develop the capabilities to counter perceived capabilities in its potential adversaries.

The official position of the US State Department is “that there is no—I repeat, no—on-going arms race in space,” according to Paula DeSutter, the Assistant Secretary for Verification, Compliance, and Implementation. In the strictest sense of the definition, this is correct. No state currently has placed objects in space that are solely intended as weapons for attacking either other satellites or targets on the ground. But this official position deliberately ignores the research and development that is ongoing into the technologies crucial for such attacks. This is done because it is currently the policy of the United States to not deploy space weapons while “hedging” against an adversary deploying space weapons by continuing the research and development of space weapons. This policy is a compromise between those on the political right who see space weapons as necessary to continued American dominance and those on the left who wish to use space for only peaceful purposes.

Part of the justification for this policy is that the US sees other nations, specifically China, developing capabilities that could be used to attack US space assets. But China also sees the United States developing capabilities to counter its national interests along with military doctrine for space dominance with clear guidelines for offensive counterspace and national policy indicating that the US can and will deny adversaries the use of space capabilities hostile to US national interests. And so China seeks to develop technologies and doctrine to counter the perceived capabilities of the United States.

These capabilities-based assessments of potential adversaries and development of counter-tactics are an essential element of sound military planning for any state, and completely within the legitimate rights of any state to conduct. But when left unchecked by policy and oversight, they will, and historically have, resulted in arms races and increased the potential for armed conflict.

These events are a litmus test that reveals what the observer wants to see.

Both the United States and China recognize the immense socioeconomic value and benefit that peaceful uses of space can provide. Both recognize the benefits to military power and international influence space can provide. Both are developing the technologies to counter each other’s military power and international influence. Both accuse each other of hiding space weaponization behind a veneer of peaceful uses. Both deny there is an arms race.

Unless there is a change of policy on this issue towards transparency and cooperation, both states will remain on this untenable collision course in space. And the end result could negatively affect space security and sustainability for not only both nations but all of humanity’s as well.

Brian Weeden (brian.weeden@gmail.com) is a technical consultant for the Secure World Foundation and former US Air Force officer with a background in space surveillance and ICBM operations.